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| United States Patent |
5,289,096
|
|
Takeda
|
February 22, 1994
|
Press machine stroke operation mechanism and operation control method
therefor
Abstract
The present invention provides a stroke operation mechanism which is
incorporated in a single-structure press machine so that various types of
stroke operations can easily be generated on the slide side, and a control
method for controlling the stroke operation mechanism so as to cause the
mechanism to exhibit various types of stroke operations. The press machine
stroke operation mechanism has a driving system having a feed screw member
disposed on a plane in parallel therewith, at least one pair of nut
members screwed on the screw member and moved by rotation of the screw
member so as to separate from and approach to each other, and a servomotor
for supplying torques for normal and reverse rotations to the screw
member; and a slide system having a slide member supported below the screw
member at right angles therewith so as to be vertically slidable, and a
transmission bar member having an upper end axially connected to the nut
members and a lower end axially connected to the slide member. The
rotational frequency and the rotational speed of the servomotor are
controlled for controlling the position and speed of the slide member
between the upper dead center and the lower dead center during the stroke
motion of the slide member, which is caused by rotation of the motor.
| Inventors:
|
Takeda; Shinya (Kawasaki, JP)
|
| Assignee:
|
Mechtro Joban International Co., Ltd. (Tokyo, JP)
|
| Appl. No.:
|
030723 |
| Filed:
|
March 12, 1993 |
Foreign Application Priority Data
| Current U.S. Class: |
318/560; 72/481.3; 83/552; 100/48; 100/289; 228/102; 318/567 |
| Intern'l Class: |
G06F 015/46 |
| Field of Search: |
318/560-646
425/451.6,451.5,149,150
300/92
360/92
414/796.9,797.8
83/552
228/107
72/405
|
References Cited
U.S. Patent Documents
| 3369160 | Feb., 1968 | Koppel et al.
| |
| 4988273 | Jan., 1991 | Faig et al. | 318/254.
|
| 5046241 | Sep., 1991 | Ricard | 29/863.
|
| 5134430 | Jul., 1992 | Koizumi | 354/320.
|
| 5157565 | Oct., 1992 | Domel | 300/92.
|
| 5164203 | Nov., 1992 | Tanaka et al. | 425/149.
|
| 5164209 | Nov., 1992 | Goto | 425/451.
|
| 5187531 | Feb., 1993 | Ozawa et al. | 355/308.
|
Primary Examiner: Ip; Paul
Attorney, Agent or Firm: Rogers & Killeen
Claims
What is claimed is:
1. A press machine stroke operation mechanism comprising: a driving system
comprising,
a feed screw member having threads in different feed directions,
at least one pair of nut members which are screwed on the threads in
different feed directions and which are moved by rotation of said screw
member so as to separate from and approach each other, and
a servomotor for selectively supplying torques for normal and reverse
rotations to said screw member; and a slide system comprising,
a vertically disposed slide member supported below said screw member at
right angles therewith so as to be vertically slidable, said slide member
having a bottom end adapted to apply pressure directly to a work piece
when said stroke operation mechanism is operated, and
two transmission bar members, each of said transmission bar members having
an upper end connected to one of said nut members and a lower end
connected to said slide member at a single location near a top end thereof
that is common to both said transmission bar members so that both said
transmission bar members apply force directly to said slide member when
said stroke operation mechanism is operated.
2. A method of controlling the operation of a press machine stroke
operation mechanism, the mechanism having (i) a feed screw member with at
least one pair of nut members screwed on said screw member that are moved
by rotation of said screw member so as to separate from and approach each
other, (ii) a servomotor for supplying torques for normal and reverse
rotations to said screw member, (iii) a slide member supported below said
screw member at right angles therewith so as to be vertically slidable to
apply pressure to a work piece, and (iv) a transmission bar member having
an upper end connected to said nut members and a lower end connected to
said slide member, the method comprising the steps of:
(a) determining said slide member's position and speed; and
(b) controlling the rotational speed of said servomotor in response to the
determined position and speed to thereby control the position and the
speed of said slide member between the upper dead center and the bottom
dead center in the stroke motion of said slide member.
3. The method of claim 2 further comprising the steps of:
(c) determining the pressure applied by said slide member to a work piece;
and
(d) controlling the pressure applied by said slide member to the work piece
in response to said determined pressure.
4. The method of claim 2 wherein said slide member is vertically disposed
and said transmission bar member is connected to an upper end of said
slide member, the method further comprising the step of applying pressure
to the work piece at a lower end of said slide member.
5. The method of claim 4 wherein said transmission bar member comprises two
rods, each of said rods having an upper end connected to one of said nut
members and a lower end connected to said slide member at a single
location near the upper end thereof that is common to both said rods.
6. The method of claim 3 wherein said step of controlling the pressure
comprises the steps of providing a predetermined pressure value and
comparing said determined pressure to said predetermined pressure value.
7. The mechanism of claim 1 further comprising a control system for
controlling the operation of said servomotor, said control system
comprising:
sensor means for determining the position and speed of said sliding member;
and
control means for controlling the rotational speed of said servomotor in
response to said sensor means.
8. The mechanism of claim 1 further comprising a C-shaped housing for said
slide system, said slide system being housed in an upper arm of said
C-shaped housing so that said bottom end of said sliding member is able to
apply pressure to a work piece disposed on a lower arm of said C-shaped
housing.
9. The mechanism of claim 1 further comprising a control system for
controlling the operation of said servomotor, said control system
comprising:
pressure sensing means for determining the pressure applied to the work
piece; and
control means for controlling said servomotor in response to said pressure
sensing means.
10. The mechanism of claim 9 wherein said control means comprises means for
providing a predetermined pressure value and means for comparing said
predetermined pressure value to a pressure from said pressure sensing
means.
11. A press machine comprising:
a sliding machine for applying pressure to a work piece at a first end of
said sliding member;
a driving system for moving said sliding member towards and away from the
work piece, said driving system comprising,
a feed screw member disposed in a direction generally perpendicular to the
direction of movement of said sliding member and having threads in
opposite feed directions,
a servomotor for rotating said feed screw member,
one pair of nut members which are moved towards or apart from one another
when said feed screw member rotates, and
two transmission means, each having one end connected to said nut members
and the other end connected to said sliding member at a second end
thereof;
a position sensor for determining the location of said sliding member;
a pressure sensor for determining the pressure applied by said sliding
member on a workpiece when said press maching is operating; and
a control system for controlling movement of said sliding member responsive
to said position sensor and said pressure sensor.
12. The press machine of claim 11 further comprising a C-shaped housing for
said sliding member and said driving system, said sliding member being
housed in an upper arm of said C-shaped housing and arranged vertically so
that said first end of said sliding member is able to apply pressure to a
work piece disposed on a lower arm of said C-shaped housing.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a press machine stroke operation mechanism
comprising a servo motor and a link mechanism, and a method of controlling
the position and speed of the stroke operation of the mechanism so that
the press machine is operated in accordance with the working contents of
the intended press work.
Press machines using a servo motor as a driving source of a stroke
operation mechanism are proposed in Japanese Patent Laid-Open Nos.
62-252700, 62-296999 and 62-297000. A press machine using a link mechanism
as a stroke operation mechanism is also known as a quick-return press or
the like.
However, the previously proposed press machines using a servo motor as a
driving source are screw presses and are developed as single purpose
machines for caulking. Thus such press machines are not intended to be
used considering the pressure applied to a workpiece, the pressure speed
or a position in a stroke where the pressure and speed are applied.
Since the link mechanism of the known link press is also incorporated into
a machine in order to simply quickly return a slide member, the same press
mechanism cannot be used for press works having different work contents.
However, if the way of applying the pressure and the pressure speed to a
workpiece can be changed for working different workpieces by a single
press machine, press machine makers need not to produce different machines
according to work contents, and the user also need not to buy and install
machines respectively required for different work contents. It is thus
thought that an attempt can be made to significantly rationalize the press
work from various viewpoints.
SUMMARY OF THE INVENTION
In consideration of the above point, an object of the present invention is
to provide a stroke operation mechanism which is incorporated into a
single structure press machine so that various types of stroke operations
can easily be produced on the slide side, and a control method for causing
the stroke operation mechanism to exhibit various stroke operation speeds.
In order to achieve the object, a stroke operation mechanism of the present
invention comprises a driving system comprising a feed screw member
disposed on a plane in parallel therewith and provided with threads in
different feed directions, at least one pair of nut members screwed on the
screw member so as to be forwardly and backwardly moved in directions in
which the nut members separate from and approach to each other by the
rotation of the screw member, and a servomotor for selectively supplying
torques for normal and reverse rotations to the screw member; and a slide
system comprising a slide member supported below the screw member at right
angles therewith so as to be vertically slidable, and a transmission bar
member having an upper end portion axially connected to the nut members
and a lower end portion axially connected to the slide member.
The present invention also provides a method of controlling the press
machine stroke operation mechanism comprising a driving system comprising
a feed screw member disposed on a plane in parallel therewith, at least
one pair of nut members screwed on the screw member so as to be forwardly
and backwardly moved in directions in which the nut members separate from
and approach to each other by the rotation of the screw member, and a
servomotor for supplying torques for normal and reverse rotations to the
screw member; and a slide system comprising a slide member supported below
the screw member at right angles therewith so as to be vertically
slidable, and a transmission bar member having an upper end portion
axially connected to the nut members and a lower end portion axially
connected to the slide member. In the control method, the rotational
frequency and the rotational speed of the servomotor are controlled for
controlling the position and the speed of the slide member between the top
dead center and the bottom dead center during the stroke motion of the
slide member, which is caused by rotation of the servomotor.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view showing a stroke operation mechanism in accordance
with an embodiment of the present invention;
FIG. 2 is a side view of an example of press machines to which the stroke
operation mechanism shown in FIG. 1 is applied; and
FIG. 3 is a block diagram showing an example of a control system of the
stroke operation mechanism shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A stroke operation mechanism and a control method therefor are described
with reference to embodiments of the present invention. FIG. 1 is a front
view showing a stroke operation mechanism according to an embodiment of
the present invention, FIG. 2 is a side view showing an example of a press
machine to which the stroke operation mechanism of the present invention
shown in FIG. 1 is applied, and FIG. 3 is a block diagram showing an
example of a control system for the stroke operation mechanism of the
present invention shown in FIG. 1.
In FIG. 1, reference numeral 1 denotes a feed screw having threads 1L and
1R which are formed in the left and right sides thereof in opposite
directions, the screw 1 being horizontally disposed. Reference numerals
2a, 2b and 2c respectively denote bearings for supporting the both ends
and an intermediate portion of the screw 1 where no thread is formed.
Reference numeral 3 denotes a servo motor connected to the right end of
the screw 1 shown in FIG. 1 through a joint 4. Reference numerals 5L and
5R respectively denote left and right nut members which are screwed on the
external threads 1L and 1R formed on the left and right sides of the screw
1. Reference numeral 6 denotes a slide guide used for locking the nut
members 5L and 5R, the projections 51 and 52 of the nut members 5L and 5R
being supported by the guide 6.
When the feed screw 1 is rotated by the servomotor 3 in a normal or reverse
direction, the left and right nut members 5L and 5R screwed thereon are
thus moved so as to separate from or approach to each other.
Reference numeral 7 denotes a vertical slide member disposed at right
angles with the feed screw 1, and reference numeral 8 a guide holder for
the slide member. When the mechanism is applied to a press machine, a
working die is provided below the lower end of the slide member 7.
In the present invention, the vertical sliding motion of the slide member
7, i.e., the stroke motion thereof, is caused by connecting the nut
members 5L and 5R to the slide member 7 through connecting members 9L and
9R, respectively. The stroke operation mechanism which is applied to a
press machine is arranged as described above.
Namely, the upper ends of the connecting members 9L an 9R are connected to
the nut members 5L and 5R by shafts 10L and 10R, respectively. On the
other hand, the lower ends of both members 9L and 9R are connected to the
upper end of the slide member 7 by a shaft 10c. When the nut members 5L
and 5R are moved on the screw 1 so as to separate from and approach to
each other, the slide member 7 thus makes a vertical stroke motion within
the guide holder 8.
The stroke operation mechanism shown in FIG. 1 is designed so that the
slide member 7 makes stroke motions for press works having various work
contents. However, the stroke operation mechanism of the present invention
is not limited to the mechanism shown in FIG. 1. For example, two feed
screws respectively having a right-hand thread and a left-hand thread are
arranged parallel, and the nut members 5L and 5R may be screwed on the two
screws and connected to the stroke member 7 through the connecting members
9L and 9R, respectively.
The stroke operation mechanism of the present invention shown in FIG. 1 can
be applied to a press machine, for example, as shown in FIG. 2. An example
of press machines provided with the stroke operation mechanisms of the
present invention is described with reference to FIG. 2. In FIG. 2, the
same reference numerals as those in FIG. 1 denote the same members.
In FIG. 2, the stroke operation mechanism of the present invention shown in
FIG. 1 is mounted on the upper portion of a C-shaped frame 11. In the
frame 11, a table or bolster 13 for holding a mold 12 such as a lower mold
or the like is formed on a surface opposite to the slide member 7.
Reference numeral 14 denotes a slide motion detection bar provided on the
slide member 7, and reference numeral 15 denotes a position detector
provided opposite to the detection bar 14. In this arrangement, a
workpiece (not shown) placed between the slide member 7 and the mold 12 is
worked on in various manners by the stroke motion of the slide member 7
caused by normal and reverse rotation of the servomotor 3 and the mold 12.
The servomotor 3 of the stroke operation mechanism in the press machine
shown in FIG. 2 is controlled by, for example, the control system shown in
FIG. 3. In FIG. 3, reference numeral 16 denotes a setting section for
setting predetermined data such as the stroke speed at a stroke position,
pressure and the like on the slide member 7; reference numeral 17, a
present data forming section for collecting data from the position
detector 15 and forming present data such as the position of the slide
member 7 during a stroke motion, the speed, the pressure applied and the
like; reference numeral 18, a reference clock of the data forming section
17; reference numeral 19, a processing section for comparing the
predetermined data of the setting section 16 and the present data of the
present data forming section 17; and reference numeral 20, a motor control
section for outputting a control signal for the servomotor 3 on the basis
of the output from the processing section 19. In FIG. 3, although the same
reference numerals as those in FIGS. 1 and 2 denote the same members, the
stroke operation mechanism except the servomotor 3 is denoted by reference
character MC. A pressure sensor 21 is also provided on the slide member 7
so that the data of the pressure sensor 21 is input to the present data
forming section 17.
As described above, during the stroke operation of the slide member 7, the
stroke speed of the slide member 7 can be controlled only by controlling
the servomotor 3 at any desired stroke position. The stroke operation
mechanism of the present invention thus permits various press works such
as shearing, coining, free bending, cold extrusion, deep drawing, swaging
and the like to be realized by a single stroke operation mechanism.
When the press machine shown in FIG. 3 is used as a multipurpose punch
press, and various set dies such as a trimming die, a notch die and the
like, all of which are standardized and commercially available, may be set
between the slide member 7 and the table 13.
As described above, the present invention provides a stroke operation
mechanism comprising a combination of a feed screw mechanism and a link
mechanism, and driven by the driving force obtained from a servomotor
which can be servo-controlled. The present invention thus has the
significant effect of enabling all press works having various types of
stroke operations or press works in a wider range than a conventional
general purpose press using a single press machine provided with the
mechanism of the present invention.
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